Add saved payout destination UX and service contracts (#54)

frontend/app/lib/workspace/summary.dart

@@ -1,3 +1,5 @@
+import 'dart:math';
+
 import 'package:flutter/material.dart';
 
 import 'package:intl/intl.dart';
@@ -6,6 +8,8 @@ import 'package:provider/provider.dart';
 
 import 'package:sxchnge_wallet/sxchnge_wallet.dart';
 
+import '../destinations/details.dart';
+
 import 'copy.dart';
 
 import '../generated/i18n/app_localizations.dart';
@@ -49,13 +53,23 @@ class TransferSummary extends StatelessWidget {
               q.request.kind == TransferKind.payout
                   ? l.wRecipientGets
                   : l.wCredit,
-              money(context, b, q.credit),
+              q.payoutTerms == null
+                  ? money(context, b, q.credit)
+                  : '${NumberFormat.decimalPatternDigits(locale: Localizations.localeOf(context).toLanguageTag(), decimalDigits: q.payoutTerms!.precision).format(q.payoutTerms!.amount / pow(10, q.payoutTerms!.precision))} ${q.payoutTerms!.assetLabel}',
               large: true,
             ),
+            if (q.payoutTerms != null) ...[
+              const SizedBox(height: 12),
+              Text(l.dTiming(q.payoutTerms!.expectedSeconds)),
+              if (p.service.isSimulated) Text(l.dDemoTerms),
+            ],
             if (q.request.kind == TransferKind.payout) ...[
               const Divider(height: 32),
               Text(l.wRecipient),
-              SelectableText(q.request.recipient),
+              if (q.payoutSnapshot != null)
+                DestinationDetailsView(details: q.payoutSnapshot!)
+              else
+                SelectableText(q.request.recipient),
             ],
           ],
         ),